<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<div id="app">
  <env/>
</div>

<script src="./js/vue.js"></script>

<template id="cpn1">
  <div>
    <h1>{{message}}</h1>
  </div>
</template>

<script>
  const app = new Vue({
    el:'#app',
    data:{
      message:'Hello World'
    },
    components:{
      env:{
        template:'#cpn1',
        data(){
          return{
            message:'Hello Component1'
          }
        }
      }
    }
  });
</script>
</body>
</html>